Continuity mistake: Near the end scene, when the three characters came to the surface, L.L. Cool J. was taken by the shark. When he was taken underwater and when he surfaced, the shark had him in her mouth on the right side. When they went under again and resurfaced, L.L.Cool J. was on the left of the shark's mouth. What? Did the shark not like him on the right side so she switched him underwater? (01:27:30)
Continuity mistake: Towards the end of the movie, the Preacher stabs the shark in its left eye with his cross, causing it to bleed. In the later scene, when shark returns to eat Susan, its eye is intact. (01:28:10 - 01:32:45)
Continuity mistake: Near the end when the survivors has reached the surface and LL Cool J gets attacked by a shark. Notice all the blood in the water. Shortly after, when he is pulled up and rescued, you see no blood at all. (01:28:20)
Continuity mistake: The man with the cross has a wound on the left hand side of his head. Later in the movie it has moved down.
Continuity mistake: When the shark rises above water with Jan partially in its mouth, its teeth are in about the level of her waist. As Carter grabs onto Jan, it moves its teeth up to the top of her chest. In the wide shot that follows, though, its teeth are back at her waist, then in the last shot of her being pulled underwater, they are up way higher again, at her chest.
Continuity mistake: At the end, Carter manages to hold onto the perimeter fence, and the shark goes through. The shark then explodes, and Carter is seen being blown off the fence back the way he came, yet when he surfaces, he's now on the other side of the fence.
Continuity mistake: When the shark jumps out of the water and grabs Russell Franklin, it slams him down with his body face-down in its mouth. A few seconds later, in the underwater shot, his body is suddenly face-up in its mouth.
Continuity mistake: In the part where they are climbing up the ladder and there's fire on the roof, just after the shark attack Preacher comes and pulls them up with knotted clothes, then he pulls it in with them through the door. When they go back the knotted clothes are there again.
Continuity mistake: When Samuel L. Jackson is grabbed by the shark (CGI) blood splatters all over the place. In the next shot the place and the water are spotless.
Continuity mistake: Carter puts a bandage on his right arm because of the blood. When he tries to shot the shark the bandage gets larger.
Answer: They viewed her as a villain because it was her research that backfired and caused all of the chaos, even though none of it was intentional and it was a mistake. But audiences can be ruthless and unforgiving at times. However, the ending did feel like a cheap cop-out that created more plot holes. And many do feel she should have survived and completed her character arc. I don't know why they never offered the ending as a bonus feature on the DVD, but fans started a petition on the Change site calling for Warner to release the original ending. Thomas Jane is on board as well, as he's promoting it on his Instagram account. So that's probably the best way to get Warner's attention if you want to see the original ending.